山东平度闫村石墨矿岩石学特征及找矿标志

Petrological Characteristics and Prospecting Criteria of Yancun Graphite Deposit in Pingdu City of Shandong Province

闫村石墨矿为赋存于古元古代荆山群陡崖组徐村段含石墨变质岩系地层中的区域变质型矿床,属角闪岩相—麻粒岩相,是中深变质作用的产物。在系统采集石墨矿石样品的基础上,对石墨矿石样品进行了化学成分、矿物组成、结构构造、矿物共伴生关系、石墨结构等较为系统的研究。结果表明:矿石中有用组分固定碳含量2.74%~5.36%,平均3.34%,还含有SiO 2,TiO 2,Al 2O 3,Fe 2O 3,FeO,MnO,MgO,CaO等;矿石矿物为石墨,脉石矿物为石英、钾长石、白云母、透辉石、透闪石、黄铁矿、黄铜矿等。越靠近地表,矿石中黏土矿物含量越高,矿物组成越复杂;石墨片径一般在0.2~1.0 mm,个别大径达1.2 mm,片厚0.03~0.05 mm。石墨片受力程度不同,局部有破碎和揉皱现象、泥化现象。闫村石墨矿属于区域变质型矿床,具有明显的找矿标志,赋矿层位、构造位置、岩性特征、岩石类型、地球物理特征,均是寻找该类石墨矿的良好标志。

Yancun graphite deposit is a regional metamorphic deposit in graphite bearing metamorphic rock series in Xucun section of Douya formation in Paleoproterozoic Jingshan group.It belongs to amphibolite granulite facies.It is the product of middle and deep metamorphism.On the basis of systematic collection of graphite samples,chemical composition,mineral composition,structures,associated relationship,and structures of graphite samples have been studied systematically.It is showed that the fixed carbon content of useful components is 2.74%~5.36%and the average value is 3.34%.It also contains SiO 2,TiO 2,Al 2O 3,Fe 2O 3,FeO,MnO,MgO,CaO,etc.The ore mineral is graphite,and the gangue mineral is quartz,potash feldspar,muscovite,diopside,tremolite,pyrite,chalcopyrite,etc.The closer to the surface,the higher the clay mineral content in the ore,the more complex the mineral composition.The diameter of graphite flake is generally 0.2~1.0mm,the large diameter is up to 1.2mm,and the flake thickness is 0.03~0.05mm.The graphite flakes are broken,crumpled and muddy in some parts due to different degrees of stress.The apparent polarizability is 4%~15%,apparent resistivity is 15~100Ω·m,and self electric anomaly is below-200mV.Yancun graphite deposit belongs to regional metamorphic type deposit,which has obvious prospecting marks.Ore bearing horizon,structural position,lithologic characteristics,rock type and geophysical characteristics are good indicators for this type of graphite deposit.